Weaving devices, commonly called looms, are known in the art and have been in existence in one or another form for thousands of years. Weaving devices are generally used for producing woven fabric. Generally speaking, weaving devices consist of a frame, a substantially horizontal array of eyelets movably supported by the frame between an upper position and a lower position, and a mechanism for moving the eyelets between the two positions.
To set up a typical weaving device for operation, a thread, or any type of weavable strand, is drawn off a spool and passed through an eyelet of the weaving device, then passed through a guide which is on the opposite side of the eyelet from the spool. The guide may be in the form of a long horizontal slot, or a gap between two horizontal, vertically opposed rollers for example. Each eyelet is threaded in this manner with an individual thread.
Selected eyelets are oriented in the upper position and slightly above the guide, while the remaining eyelets are oriented in the lower position and slightly below the guide. This difference in the relative positions of the eyelets with respect to each other and to the guide, causes the threads to form an upper and lower row of parallel threads. The upper row passes from the upper eyelets to the guide, and the lower row passes from the lower eyelets to the guide. The two rows intersect, or meet, at the guide to form an acute interior corner or angle. This formation of two rows of threads is generally called a shed. Thus, a shed can basically be described as two flat planes, each formed by a row of parallel threads, which meet to form a trough, or corner.
To begin the weaving process a cross-thread, called a weft thread, is placed into the corner of the shed where the threads meet at the guide, and perpendicular to the warp threads. After placement of the weft thread, the position of each eyelet is reversed, that is, the upper eyelets move to the lower position, and the lower eyelets move to the upper position. This change in position of the eyelets not only forms another shed, but also causes the warp threads to partially wrap around the weft thread. A second weft thread is then inserted into the corner of the new shed, and the position of each eyelet is again reversed. This process is continually repeated to form a fabric created from interlacing, or weaving, the warp and weft threads.
Basic woven fabric is produced on weaving devices which move the respective eyelets in a continuously repeating sequence of shed changes to produce a substantially homogeneous fabric pattern. However, a special type of weaving device, called a Jacquard device, may be used, for among other purposes, to weave intricate or varying patterns into the fabric, or to perform seaming operations in which the opposite edges of a piece of fabric are woven together to form an endless ribbon or belt of fabric. Jacquard devices are well known in the art and have been in existence for hundreds of years in various forms. In a Jacquard device, each eyelet is individually selectively movable with respect to each of the shed changes. In other words, the sequence of movements of the eyelets is not merely uniformly repetitive, but may be selectively variable with each shed change. In this manner, varying and stylistically appealing patterns may be woven into the fabric by the weaving device.
Generally speaking, a Jacquard weaving device consists of an array of springs mounted on the top of the frame of the weaving device. An eyelet is attached to each of the springs and depends from the lower end of the spring. The respective springs bias the eyelets toward an upper position. A pulley block is attached to the lower side of each eyelet and depends below the eyelet. A cord is fed or otherwise received through the pulley block and engages the sheave, or pulley wheel of same. The opposite ends of the cord depend from the pulley block. The cord has two hooks attached to it, one on each end.
Attached to the frame, are griff bars which reciprocally move up and down below the pulley block. The griff bars are mechanically linked together so that, as one griff bar moves up, the other correspondingly moves down, and vice versa. An actuator such as an electrical motor is coupled to one of the griff bars to reciprocally move the griff bars at continuously selective and repeating intervals.
The hooks slidably engage guides which are mounted on the frame. The respective guides restrict and direct the path of movement of the hooks such that the path of movement of one of the hooks substantially coincides with one of the griff bars, and the path of movement of the other hook substantially coincides with the other griff bar. Each hook has a slot formed therein which is engaged by the respective griff bar as it moves downwardly. If the hook is held in its lowermost position, the slot formed on the hook allows the griff bar to disengage from the hook and move upwardly while leaving the hook in its lower position.
The cord which extends between the respective hooks is of such a length that the individual springs, located above each of the eyelets, keeps the cord taut at all times. When both hooks are engaged by the respective griff bars, the hooks and cord travel in a seemingly see-saw like motion along with the griff bars. During this motion the cord is pulled back and forth through the pulley block and rollingly engages the sheave. Also during this pattern of motion, the pulley block and eyelet remain substantially stationary (in the upper position) being held in the same position by the tension of the spring.
In these weaving devices the lower end of each hook is engageable by means of a latch which is mounted on the frame and which is located near the bottom of the path of travel of each of the hooks. Each latch selectively captures and retains the respective hook in the lower position. If one of the hooks is held in its lower position by the respective latch, the associated griff bar disengages from the hook as it travels upwardly, leaving the hook retained by the latch in the lower position. As the griff bar moves upwardly, leaving the associated hook retained by the latch, the other hook (attached to the opposite end of the cord) is simultaneously pulled downwardly toward another latch by the other griff bar. Because the first hook is latched in the lower position, and is not allowed to travel upwardly while the other hook is being pulled downwardly, the pulley block is simultaneously pulled downwardly by the cord attached between the hooks. This action, of course, pulls the eyelet downwardly against the upwardly biasing force of the spring attached to same. This results in the eyelet reaching a lowermost position as both hooks reach their respective lowermost positions.
For the eyelet to remain in the lower position, both the first and second hooks must be retained in their respective lowermost positions by their respective latches. In this manner, the individual griff bars continue to reciprocally move in a see-saw like motion above both hooks, but do not cause movement of the hooks, cord, pulley block, or eyelet. Conversely, for the eyelet to move to its upper position once again, one of the latches must disengage from one of the hooks as the associated griff bar is located in the lowermost position. In this manner, one of the hooks is released by the latch and allowed to travel upwardly with the griff bar to its upper position under the influence of the spring. This action results in the respective pulley block and eyelet moving upwardly to the original upper position. For the eyelet to remain in the upper position, the other latch must also release its respective hook, allowing the see-saw like motion of the hooks and cord to resume as initially described.
Many Jacquard weaving devices utilize electric solenoids to effect the selective retention of the hooks by the latches. In this type of design, an electric solenoid is mounted on the frame near each of the respective latches. Mounted on each latch is a material which can be magnetically influenced, or attracted, such as iron, when the solenoid is energized with electrical current. Generally, each latch is biased into a first, or latched, position. During operation, as a hook is moved into engagement with the respective latch, the hook pushes the latch into a second, or unlatched position, and in the direction of the solenoid such that the magnetically attractable material is pressed against or moved closely adjacent to the solenoid. In the situation where the solenoid is energized, the material is strongly attracted to the solenoid by the magnetic field. This in turn holds the latch in the unlatched position which prevents the latch from capturing and retaining the hook in the lowermost position as the hook moves upwardly and away from the respective latch.
On the other hand, if the solenoid is not energized, the bias of the latch causes the latch to move back to the latched position as the hook begins to move upwardly. In this scenario, before the hook completely disengages from the latch, the latch captures the hook, thereby retaining it in the lowermost position. If the hook is retained by the latch, the griff bar will disengage from the hook and continue moving upwardly while leaving the hook in its lowermost position. However, the subsequent downward movement of the griff bar will again move the hook against the respective latch in a manner which will cause movement of the latch to the unlatched position. This enables the hook to be subsequently released from the latch if the latch had been held in the unlatched position by the solenoid. In this manner, the weaving device selectively moves the eyelet by energizing and de-energizing the solenoids at given intervals which controls the movement of the hooks. Often a controller, such as a programmable logic computer, is utilized to control electrical current flow to the solenoids and related motor which propels the individual griff bars.
Commonly, a Jacquard weaving device consists of at least one row of eyelets which are configured as discussed above, with respective springs, pulley blocks, cords, hooks, latches and solenoids for each eyelet. Usually, the entire row of eyelets is served by a single pair of elongated griff bars. In this manner, each individual eyelet in the row may be moved from either the upper position to the lower position, or vice versa, or may remain in either the upper or lower position with each reciprocal stroke of the griff bars. Often, large Jacquard weaving devices consist of several such rows of similarly configured eyelets, each with its own set of griff bars. Thus, by moving the griff bars at repeating intervals, and selectively controlling the energization of the solenoids, the controller can cause any combination of eyelets to either move up or down, or remain in the upper or lower positions, with each shed change.
While Jacquard weaving machines of conventional design have been operated with varying degrees of success, there have been recognized shortcomings which have detracted from their usefulness. For example, a relatively large Jacquard weaving machine may consist of a dozen or more rows of eyelets, each row having up to thirty or more eyelets. Such a machine, having hundreds of individually movable eyelets, will have a complex, tightly packed mechanism comprised of interactive, precision components, including griff bars and related drive trains, hooks, latches, solenoids, cords, guides, and pulley blocks. Thus, a malfunction or failure of a single component in this complex, tightly packed mechanism necessitates a tedious and time-consuming disassembly of the machine in order to simply gain access to the failed or malfunctioning part for removal and replacement. This tedious disassembly process of the machine results in costly down-time of the weaving device, during which the operation of the device is temporarily halted.
Therefore, it has long been known that it would be desirable to provide a Jacquard weaving machine which achieves the benefits to be derived from similar prior art devices, but which avoids the detriments individually associated therefrom.